1. Field of the Invention
The present invention relates to an accounting apparatus and an accounting method for billing for the use of ink in a printer. The invention also relates to a computer-readable program storage medium for storing a program having an accounting function.
2. Description of the Related Art
Hitherto, typical methods for printing out hard copies include an electrophotographic printing method, an ink-jet printing method, a wire-dot printing method, a thermal recording method, and a thermal transfer recording method. Among these methods, the ink-jet printing method is coming into wide use because of the quality of printed characters and photographs, compatibility with various devices, such as computers and digital cameras, printing speed, and quiet operation. In the ink-jet printing method, ink is discharged from fine holes in an ink-discharge head to a recording medium. Printers using this method are less noisy and comparatively small, and thus, their market share is increasing.
Printers using the ink-jet printing method are often used in homes and offices because of their ease of use and general versatility. The amount of ink spent in these environments is smaller than that used for industrial purposes, and thus, the ink is often stored in a small-capacity ink tank installed in the printer.
Basically, there are two types of structures for the ink tank and the discharge head in the printer. In the first type of structure, the ink tank and the discharge head are separately disposed from each other, and a flexible tube is disposed in an ink passage to connect the ink tank and the discharge head. In the second type of structure, the ink tank and the discharge head are integrated into each other, and the ink is directly filled in the discharge head (ink cartridge). In both types of structures, when the ink runs out, printing can no longer be performed. It is thus necessary to refill the ink or to replace the ink cartridge.
In the second type of structure, when one color of ink runs out in an ink cartridge containing a plurality of colors of ink, the whole cartridge must be replaced. Accordingly, the user has to discard the other colors of ink which can still be used, thereby hampering the effective use of the ink.
One measure to solve this problem is to form an ink tank cartridge containing only one color of ink. With this arrangement, however, the user has to prepare a plurality of ink cartridges for the individual colors of ink as a stock.
Additionally, in the ink cartridge integrating the ink tank and the discharge head therein, if the discharge head does not properly function, the whole cartridge must be replaced even though the ink does not run out. In this case, the user has to discard the whole ink cartridge regardless of whether the ink cartridge is still full of one color of ink or a plurality of colors of ink. This also prevents the effective use of the ink.